Refers to the chalkline drawn around a corpse in movies. The 'line' idea is mostly fictional, since it contaminates the crime scene investigation, but it serves as more dramatic metaphor for murder.
You better watch how you're talking and where you're walking, or you and your homies might lined in chalk. (Coolio - Gangsta's Paradise)
When a woman with a fatherless child tries to get a new guy to be the new father within a few weeks of dating. He's getting 'fast-laned' into a family he didn't start.
"Mikey's only been with her a month and the kid's calling him 'Dad'. I think he's getting fast-laned!"
"Andy nobody in our gan digs movies and books the way I do. For a while there, I thought I was the only person in the world that did. So I loned it."
-The Outsiders, S.E. Hinton